The purpose of this investigation is to establish whether medical screen-film imaging systems can be used intra-orally to accomplish the same diagnostic task as currently used dental non-screen films. It is widely accepted that use of medical screen-film imaging systems can result in dose reductions of close to 100%. The task to be investigated in the first phase of this project will be the diagnosis of the interproximal caries. Difficulty in diagnosing incipient caries or determining the extent of non-incipient caries appear to be the main reasons dentists are reluctant to switch to faster imaging systems. Extracted teeth mounted in typodonts will be radiographed in a fixed and reproducible alignment between the x-ray source and image receptor. The image receptors used will be Kodak Ektaspeed and Ultraspeed film, Xeroradiographic Cassettes and a slow, medium and fast medical screen-film imaging system. The radiologic performance of the image receptors including speed, contrast, and resolution will be established. The radiographs produced with the various image receptors will be coded, mounted, and scored for the presence, extent and confidence in diagnosing interproximal caries by independent examiners consisting of general dentists and oral radiologists. The teeth will be sectioned and examined by laser fluorescence for the presence and extent of caries. The sectioned teeth will also be stained and examined with acid red dye. The teeth will be sectioned further and examined with microradiography for the presence and extent of caries. The three modalities of acid red dye, laser fluorescence and microradiography will be compared for the presence and extent of caries. Microradiography will establish the presence and the depth of the carious lesions and baseline truth. The results of the examiners will be compared with baseline truth with Receiver Operator Characteristic (ROC) analysis. The various image receptors will be compared to establish their performance with the diagnostic task of caries diagnosis. The diagnostic performance of the examiners including inter and intra examiner error will also be established.